Phytochemical composition of Moroccan saffron accessions by headspace solid-phase-microextraction

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1 2015; 2(4): 1-7 ISSN: AJEONP 2015; 2(4): AkiNik Publications Received: Accepted: Lage Mounira Melai Bernardo Department of Industrial Chemistry c/o via Bonanno Pisa Italy. Cioni Pier Luigi Department of Pharmacy, University of Pisa, Via Bonanno 6, I Pisa, Italy. Flamini Guido Department of Pharmacy, University of Pisa, Via Bonanno 6, I Pisa, Italy. Gaboun Fatima Bakhy Khadija Zouahri Abdelmjid Pistelli Luisa Department of Pharmacy, University of Pisa, Via Bonanno 6, I Pisa, Italy. Correspondence: Lage Mounira URAPVCRP, B.P Instituts, Rabat, Morocco Phytochemical composition of Moroccan saffron accessions by headspace solid-phase-microextraction Lage Mounira, Melai Bernardo, Cioni Pier Luigi, Flamini Guido, Gaboun Fatima, Bakhy Khadija, Zouahri Abdelmjid and Pistelli Luisa. Abstract The phytochemical composition of 19 saffron samples collected under different Moroccan environments is evaluated by Headspace Solid-Phase Micro-extraction coupled with gas chromatography mass spectrometry. The aim is to categorize Moroccan saffron volatiles and to highlight the impact of the environment on the chemical composition of the spice. This is the first research conducted on Moroccan saffron volatiles according to their geographical origin. A total of 57 volatile components have been identified. Differences in compound proportion and composition among the accessions were observed. The main chemical classes of volatiles identified were monoterpene hydrocarbons (6 to 42%), oxygenated monoterpenes (3 to 29%) and non-terpene derivatives. Only 14 compounds were found in common to all the accessions. The most important, in decreasing proportions, are safranal, 1, 8-cineole, 4-keto-isophorone, isophorone and α-pinene. 70% of the accessions analyzed contain β-isophorone, an isomere of isophorone which is a criterion of saffron high quality. Other components are identified in very few accessions, in lower amount, e.g., rose oxide (26% of accessions), allo-ocimene (13%) and piperitone (4%). A difference in the volatiles composition has been noticed consequently to accessions origin and drying mode. The cluster analysis based on Jaccard similarity and complete link method has identified five groups, at 75% of similarity. This study highlights the impact of the environment on saffron volatiles composition when the drying is done naturally, and this could be used as chemical fingerprinting for the authenticity of the product, according to its origin. Keywords: Crocus sativus L, spice, SPME-GC-MS, environment, drying mode, Jaccard Index. 1. Introduction Saffron spice has many uses based on its colour, aroma and taste. The most important are in food industry and cuisine as a dye, but it is also used for medicinal purposes. Saffron extract has been reported to show interesting anti-tumor activity [1]. Morocco is the only country in Africa and MENA region that produces saffron spice. The use of Moroccan saffron for medicinal purposes and as a dye has a long history and has been practiced for centuries [2]. The actual area of saffron cultivation is around 1000 ha. Its area of production is mainly in the south of Morocco, especially in the Anti-Atlas Mountains, and takes more and more importance in other area, particularly in the high Atlas Mountains. Most of the saffron drying is done naturally, mostly in shade, for 5 12 days according to climatic conditions. Saffron quality depends on the concentration of its three major metabolites providing the unique colour, flavour and odour to the style-stigmas. During the dehydratation and storage processes of saffron, the hydrolysis of picrocrocin (monoterpene glycoside) that is considered to be the main bitter principle of saffron and precursor of safranal, yields a monoterpene aldehyde that constitute one of the main components of saffron volatiles and responsible for its aroma [3-6]. The amount of this volatile component in dried styles-stigma structures is among the most important indicator of saffron quality. Apart from safranal, other volatile constituents contribute to the final aroma of saffron [7-11]. Several investigations have been previously carried out on saffron volatiles and more than 90 volatiles have been identified [12, 13]. According to some authors, most of the volatiles are derived from the thermal degradation of carotenoids and hydrolysis of glycoside precursors [14]. Many studies have been conducted on the techniques of saffron volatile extraction and identification [15, 16]. Among them, an easy technique based on Head-Space Solid Phase Micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) has been then proposed for preconcentration ~ 1 ~

2 and detection of many organic compounds. This method has been proven to be a powerful technique [17]. According to [18], HS-SPME has a high discriminating ability for the isolation of volatile phytochemical components and yields a high number of total organic volatiles. This method has reduced decomposition of plant compounds, and decreases the loss of these constituents. It has been previously applied to food volatile analysis [19] and since then has been used in significant applications in food aroma [20]. Volatiles components in Moroccan saffron have never been investigated before. This research permitted the identification of volatiles of some Moroccan representative accessions collected under different environments, mainly in the principal saffron regions (Taliouin and Taznakht), as well as other regions where saffron is dried naturally and conserved at farm level. A comparison was done with some samples dried by oven. Therefore, the main aim of the present study is to provide a description of the Moroccan saffron volatile profiles and its variability among Moroccan saffron landraces. 2. Materials and methods 2.1 Plant material collection Nineteen saffron samples, from various environments, dried naturally or by oven, were collected for analysis during 2011.Twelve samples were collected from the main saffron zone in the south of Morocco (S1-S11 and S14), one from Ourika region (Marrakech, S12), two from Errachidia region (East region: S13, S15), one from the North of Morocco (Tetuan: S16) and one from Kosovo (S17). Two samples are bought from cooperatives: one as a PDO (Protected Designation of Origin) product (S18) and one as a bulk sample (S19) bought from the main saffron market in Morocco. All saffron samples were produced during Geographical data were collected and soils were chemically and physically analyzed (Table 1). 2.2 Sample preparation Dried styles-stigma (0.2 g) were put into a 4 ml sealed glass vial for 48 h at room temperature and then one hour in an oil bath at 30 C to equilibrate. 2.3 Sampling of Volatile Compounds Polydimethylsiloxane fibres (100 μm) were mounted in a SPME manual holder (Supelco, Bellefonte, PA, USA). Fibres were conditioned prior to analyses, according to the manufacturer recommendations. The fibre was maintained over the sample for 1 min. After the sampling time, the fibre was withdrawn into the needle, then transferred immediately to the injection port of GC. 2.4 Chromatographic analysis of the volatile components The compounds collected from the headspace above saffron samples were analysed by a gas chromatograph (GC) connected to a mass spectrometer (MS). GC-MS analyses were performed with a Varian CP3800 gas-chromatograph equipped with a DB-5 capillary column (30 m x 0.25; coating thickness, 0.25 μm) and a Varian Saturn 2000 ion trap mass detector. Analytical conditions were as follow: injector and transfer line temperature, 220 and 240 C, respectively; oven temperature programmed from 60 to 240 C at 3 C min; carrier gas, helium at 1 ml/min; splitless injection. 2.5 Volatiles Identification Identification of the constituents was based on comparison of the retention times with those of authentic samples, comparing their linear retention indices relative to the series of n- hydrocarbons, and on computer matching against commercial [21, 22] and home-made library mass spectra built up from pure substances and components of known oils and MS literature data [23, 24, 25, 26, 27]. Moreover, the molecular weights of all the identified substances were confirmed by GC-CIMS, using MeOH as CI ionizing gas. 2.6 Data Analysis Statistical analyses were based on Jaccard similarity index and complete link method was used for comparing the similarity and diversity over samples for discrimination based on their volatile composition. 3. Results and Discussion 3.1 Sample Volatile identification Globally, 57 volatile compounds have been identified (Table 2). Quantitative and qualitative differences have been found among samples. However, only qualitative difference, based on presence and absence of molecules, is analysed in this paper. Fourteen volatiles are common to all accessions (Figure 1), with safranal (2,6,6-trimethyl-1,3-cyclo-hexadien-1- carboxaldehyde) as the main constituent (9-57%), followed by monoterpene hydrocarbons (6-42%) (Table 2). According to Maggi and co-workers [28], safranal is the major saffron volatile component, and constitutes about 60% of volatile fraction. The differences in safranal and other main volatile compounds in saffron depend mainly on the conditions of processing, storage and of volatile isolation and analysis. Some components are found in most samples in lower amounts, such as hexanal (0-1.1%), heptanal (0-0.5%), fenchone (0-0.9%), -thujene (0-0.5%), menthone (0-0.5%), linalool (0-0.4%), verbenone (0-0.4%) (Table 2). Others are found at traces level in many accessions, such cis- -ambrinol, (E)-geranyl acetone and (E)-β-ionone. Additional components are found in lower amount but in very few accessions, e.g., rose oxide (26% of accessions), allocimene (13%), piperitone (4%) (Table 2). Seven major compounds are dominant in all samples, specifically safranal (9-57%), 1,8-cineole (3-27%), 4-ketoisophorone (3-22%), isophorone (2-20%), α-pinene (1-15%), 2,6,6-trimethyl,1,4-cyclohexadien-1-carboxaldehyde (safranalisomer) (1-3%) and β-isophorone (0.6-6%) (Figure 1). Besides, some minor components are present in all samples such as 2(5H)-furanone, camphene, myrcene, α-phellandrene, δ-3-carene, α-terpinene, p-cymene and 4-methylene isophorone. According to a study conducted on saffron volatiles, β-isophorone, an isomer of isophorone, is considered one of the quality marker compounds for category I, and thus saffron containing this compound is of the highest quality [29]. 70% of samples analyzed in this study contain β-isophorone (Table 2). 3.2 Distribution of volatile components according to their environment and drying methods The matrix shown in table 3 is based on the Jaccard's similarity coefficient and indicates a high level of variation among the accessions from different sites based on volatiles ~ 2 ~

3 components. The similarity coefficient ranged from 0.48 to 0.91, with S15 (Errachidia) and S18 (PDO) having the highest chemical composition similarity (0.92). On the other side, S3 (Taliouin) together with S15 (Errachidia), possessed the least similarity coefficient (0.48) (Figure 2). Five most typical groups at 75% of similarities were then identified (Table 4). Statistical analysis shows that the composition of each sample is mainly due to both the drying method and the environment. Table 4 shows different sites assembled based on their volatile components similarity. It can be noticed that the G5 group includes samples that originated from different environment (Marrakech, Errachidia, Kosovo and an AOP product), which are all artificially dried, by oven (Table 1). This may suggests that the drying method is a dominant variant in saffron aroma expression and the environment impact is not noticeable when the drying is made by oven. So according to this result the saffron volatiles can t be a tool for discrimination of authenticity of saffron origin, when the drying is done artificially. All the other groups contain samples naturally dried. G2 include one identified sample (S4) and one unknown sample sold in the market (S19) in the saffron main region of Morocco. G1, G3 and G4, each include samples from the neighboring regions, having similar drying climatic conditions. Cluster analysis was performed to obtain groups having similar common qualitative traits (Figure 2) based on volatiles. Five groups with some similarities were then identified. In the dendrogram (Figure 2), we see that the samples S11, S13 and S16 are completely separate from all the others which indicate that the distributions of volatiles in those samples are significantly different from the distribution in the remaining samples and between them. They originated from 3 different environments (Table 1) and have been dried under natural conditions. We notice also that S1 and S3 showed some similarity at 65% but are separate from the other samples. Those two samples were dried naturally, but with sun exposition and not in shade. As we noticed in all samples originated from different environments, the volatiles composition varied according to the environment and the drying method. According to [30], storage can also be considered as responsible for the variation in aroma components in saffron.this study shows clearly that when samples are dried by oven, the environment impact is not noticeable. But when it is performed naturally, a difference between samples aroma from different environment is obvious. Fig 1: Representative chart of phytochemical composition (%) of accessions analysed ~ 3 ~

4 Fig 2: Dendrogram obtained by hierarchical clustering analysis based on saffron volatile components of 19 Moroccan accessions 4. Conclusion The volatile profiles of different Moroccan saffron samples, collected from different regions were described for the first time in this study. The site-to-site variability in saffron volatile composition is essential to understanding geographical patterns of accession diversity and the variable controlling the volatile composition. A difference has been observed on some accessions depending on the environment and drying method, which might be useful for a first discrimination. A match between chemical identification and environment was noticed for samples with natural drying. Jaccard similarity method allowed a discrimination of the samples, based on their chemical composition. This study could form the basis to other incoming studies on saffron product based on multivariate analysis including complete climatic data analysis that influence volatiles during natural drying in order to produce an original product with some peculiarities to protect quality, sustainability, and safety of saffron production in small farms. 5. Acknowledgement This study was conducted within the EMAP (Edible Medicinal and Aromatic Plants) project, under Marie Curie action call (FP7-PEOPLE-2009-IRSES) N The author wishes to thank all the Moroccan staff in INRA that helped at field work collect and laboratory analysis. Table 1: Samples origin and site identification Serial Numbers Site Origin Lat./Long. Altitude Soil Ph Organic Matter Clay (m) (Water) ( %) (%) Drying Mode S1 Taliouin / , Natural/Sun S2 Taliouin / Natural/Shade S3 Taliouin / Natural/Sun S4 Taliouin / Natural/Shade S5 Taliouin / Natural/Shade S6 Taliouin / Natural/Shade S7 Taliouin / Natural/Shade S8 Taliouin / Natural/Shade S9 Taznakht 30.57/ NI Natural/Shade S10 Taznakht 30.57/ NI Natural/Shade S11 Taznakht 30,.57/ NI Natural/Shade S12 Marrakech 31.63/ NI Oven S13 Errachidia 31.93/ NI Natural/Shade S14 Taznakht 30.57/ ,80 NI Natural/Shade S15 Errachidia 31.93/ NI Oven S16 Tetuan 35.57/ Natural/Shade S17 Kosovo 42.60/20.90 NI > 35% Oven S18 PDO (Cooperative) NI NI NI Oven S19 Saffron Market NI NI NI Natural/Shade NI: Not identified, Lat./Long. : Latitude and Longitude ~ 4 ~

5 Table 2: Volatile Components of 19 Saffron accessions: GC-MS analytical results of saffron spice accessions Volatile component RI* Minimum % Maximum % % of samples containing this components Hexanal 802 tr Heptanal 900 tr (5H)-furanone α-thujene 931 tr α-pinene camphene sabinene 977 tr heptanol β-pinene methyl-5-hepten-2-one 986 tr myrcene α-phellandrene δ-3-carene α-terpinene p-cymene limonene ,8-cineole β-isophorone (E)-β-ocimene 1051 tr γ-terpinene 1062 tr α-methylbenzylalcohol (E,E)-3,5-octadien-2-one 1068 tr fenchone camphenone , linalool n-undecane cis-rose oxide ,6,6-trimethyl-1,4- cyclohexadiene carboxaldehyde (isomer of safranal) isophorone alloocimene 1130 tr tr 13 4-keto-isophorone isomenthone menthone 1154 tr dihydro-oxophorone ,4-dimethylbenzaldehyde 1180 tr tr 13 naphthalene 1182 tr safranal methylene isophorone 1219 tr piperitone 1253 tr tr 4 bornylacetate 1285 tr tr 4 geranylformate 1298 tr dihydrocitronellol acetate 1319 tr tr 4 α-copaene 1376 tr tr 4 ethyldecanoate 1395 tr tr 4 n-tetradecane 1400 tr dodecanal 1408 tr tr 9 β-caryophyllene 1418 tr tr 4 cis-α-ambrinol 1438 tr (E)-geranylacetone 1454 tr α-humulene 1456 tr tr 4 (E)-β-ionone 1485 tr tr 74 β-himachalene 1499 tr tr 4 n-pentadecane 1500 tr tr 4 Dihydroactinolide 1537 tr tr 4 n-hexadecane 1600 tr n-heptadecane 1700 tr tr= traces; *RI, linear retention indices relative to C6-C28 n-alkanes on thehp-5 column, ~ 5 ~

6 Table 3: Jaccard similarity matrix of distances based on the presence-absencebetween all pairs of 19 saffron accession Sites S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S1 1 S2 0,742 1 S3 0,647 0,667 1 S4 0,606 0,727 0,639 1 S5 0,742 0,813 0,714 0,781 1 S6 0,676 0,794 0,658 0,765 0,848 1 S7 0,676 0,743 0,750 0,765 0,848 0,829 1 S8 0,611 0,722 0,641 0,743 0,771 0,806 0,857 1 S9 0,677 0,806 0,568 0,719 0,806 0,788 0,788 0,818 1 S10 0,618 0,788 0,564 0,657 0,735 0,722 0,722 0,750 0,781 1 S11 0,600 0,667 0,590 0,639 0,714 0,800 0,750 0,684 0,706 0,694 1 S12 0,625 0,697 0,526 0,618 0,697 0,735 0,686 0,765 0,6875 0,727 0,611 1 S13 0,622 0,561 0,500 0,500 0,600 0,634 0,595 0,619 0,590 0,625 0,571 0,632 1 S14 0,600 0,765 0,550 0,639 0,714 0,750 0,703 0,730 0,813 0,848 0,722 0,657 0,610 1 S15 0,690 0,710 0,486 0,625 0,710 0,697 0,697 0,727 0,759 0,800 0,618 0,821 0,639 0,719 1 S16 0,618 0,639 0,525 0,657 0,686 0,676 0,722 0,800 0,727 0,714 0,605 0,727 0,585 0,649 0,8 1 S17 0,594 0,667 0,541 0,588 0,667 0,706 0,657 0,735 0,656 0,697 0,541 0,893 0,649 0,629 0,852 0,697 1 S18 0,621 0,645 0,514 0,563 0,645 0,636 0,636 0,667 0,690 0,733 0,559 0,750 0,629 0,656 0,917 0,733 0,846 1 S19 0,618 0,735 0,649 0,813 0,788 0,771 0,824 0,800 0,781 0,818 0,743 0,676 0,585 0,743 0,742 0,765 0,647 0,677 1 Table 4: Grouping (G) at 75% of similarity G1 G2 G3 G4 G5 S2, S9 S4, S19 S7 S8 S10 S14 S12 S17 S5 S6 S15 S18 6. 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